195258-40-3Relevant academic research and scientific papers
Synthesis and characterization of new alkyl-carbon dioxide compounds and the first neutral acyl-carbonyl niobocene complexes
Anti?olo, Antonio,Carrillo-Hermosilla, Fernando,Del Hierro, Isabel,Otero, Antonio,Fajardo, Mariano,Mugnier, Yves
, p. 4161 - 4166 (2008/10/08)
The olefin-hydride complexes Cp′2Nb(H)(η2-RHC=CH2) (Cp′ = η5-C5H4SiMe3; R = H (3), C6H5 (4, endo isomer)) were prepared by the alkylation reactions of [Cp′2NbCl]2 (1) with the appropriate Grignard reagents RMgX (R = CH2CH3, CH2CH2C6H5) followed by a stereoselective β-elimination from the intermediate alkyl complexes Cp′2Nb(CH2CH2R). Complexes Cp′2Nb(H)(η2-RHC=CH2) (R = C6H4CH3 (5), C6H4OCH3 (6)) were prepared as a mixture of endo and exo isomers by reaction of Cp′2NbH3 (2) with the corresponding olefin. Furthermore, reactions of CO with 3 and 4, and the reactions of CO2 with 3-6, afforded the alkylniobocene complexes Cp′2Nb(CO)R (R = CH2CH3 (7), CH2CH2C6H5 (8)) Cp′2Nb(η2-CO2)(R) (R = CH2-CH3 (9)), CH2CH2C6H5 (10), CH2CH2C6H4CH3 (11), CH2CH2C6H4OCH3 (12)). The reactivity of 9 and 10 toward the strong Lewis acid B(C6F5)3 was also studied; in a first step the adducts Cp′2Nb(η2-CO2-B(C6F 5)3)(CH2CH2R) (R = H (13), C6H5 (14)) were formed and subsequently evolved to give the oxo - alkyl complexes Cp′2Nb(O-B(C6F5)3)(CH 2CH2R) (R = H (15), C6H5 (16)) with the loss of CO. Finally, reactions of 3 and 4 with CO under appropriate conditions gave the neutral acylniobocene complexes Cp′2Nb(CO)(η1-C(O)CH2CH2R) (R = H (17), C6H5 (18)), which were alternatively prepared from the reactions of 7 and 8 with CO. The different complexes were characterized by spectroscopic methods.
